An edited version of this aritcle appeared in the Nepali Times 23 Feb - 1 Mar 2018 #898
The mountain environment is rapidly
changing. The climate of recent times is breaking down, leading to warming
temperatures and changing precipitation patterns, which directly impact
Himalayan glaciers. Nepal is home to
some of the highest altitude glaciers in the world, yet many will diminish to
shadows of their former selves in the coming centuries. Glaciers are retreating
to pockets of sun-hidden refuge, where lower air temperatures prolong their
existence in the shade of the high mountains. The calm of this environment is
enjoyed by many. Tourists are transient but many Nepali call this landscape of
extremes their home. Whilst scientific research is still working to understand
how rapidly glaciers will disappear, working with those affected to mutually
share observations and adaptation strategies is now critical. Glaciers are vast
reservoirs of water, pathways to the highest peaks on earth and home to
communities of living things. When experiencing their beauty, we also should
consider their demise and be proactive towards global strategies to slow the
rate of change and engage with sustainable adaptation strategies.
Glaciers are intrinsically linked to
and indeed shape the mountain environment. In turn, sediment and rock
transported onto the surface of debris-covered glaciers shapes their evolution.
This insulating layer of rocks and sediment can reach several metres thick and
obscures the vast thickness of ice beneath. Yet these glaciers are shrinking
rapidly. Khumbu Glacier, thinned by an average of ~1 m per year (1984‒2015) where the insulating debris
is thinnest close to Everest Basecamp. The spatial distribution of thinning
leads to a flatter glacier profile, although local relief can still exceed tens
of metres. A flatter glacier is more prone to water ponding on the surface,
which can eventually form large glacial lakes. When ice is melting faster than
the replenishment at higher elevations, the glacier also slows down, which also
promotes ponding. At Everest Basecamp, Khumbu Glacier is flowing down-valley at
over 30 metres per year. Yet there is virtually no movement 7 km further down
the glacier adjacent to the village of Lobuche. Exposed ice cliffs and
supraglacial ponds (existing on the glacier surface) are hot-spots of melt. The
ponds absorb and transmit thermal energy into the glacier interior, such that
the process can become a positive feedback loop, leading to an expanding
network of ponds. With a pond at their base, ice cliffs rapidly retreat across
the glacier, generating meltwater and leaving a trail of fallen debris.
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| Supraglacial ponds on a stagnating part of Khumbu Glacier |
Stagnating glaciers provide new
habitat for birds, bees, small mammals, macroinvertebrates (small critters
living in ponds), and occasionally grazing livestock. Vegetation grows when the
glacier slows and the surface stabilises. However, when lakes develop the
situation can become problematic. When dammed by a wall of sediment and rocks
of unknown stability, these lakes can threaten downstream communities and
require close monitoring using satellite imagery and in the field. The
hydropower potential of these lakes could one day be tapped, however, some
lakes will inevitably breach their dams and cause downstream flooding, often
triggered by large avalanches. Awareness, early warning, and adaptation is key.
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| Thulagi Glacial Lake |
Access to water resources will
change as snow cover reduces and glaciers disappear, also requiring community
adaptation. There is often disconnect between scientists, mountain communities,
transient mountain visitors, and government and non-government agencies.
Scientists should be open about observed and predicted changes, but also the
associated uncertainties. Open Access publishing allows scientific research to
be read by all. Communities can retain vast historical knowledge of previous
environmental stresses, and are well placed to describe ongoing changes and
their adaptation requirements. Engagement is therefore key for research to be
targeted efficiently and used to guide adaptation strategies.
Anyone can volunteer time and
become a citizen scientist: communities, mountaineers and tourists can all
contribute to targeted data collection and analysis. Communities are well
placed for continual observations targeted to local needs, such as stream and
river flows, timing of the growing seasons, and documentation of flood events.
Local and international mountaineers access the highest peaks on earth and can
bring back snow and rock samples, maintain weather stations, capture repeat
photography and provide specialist knowledge of changes in the high-mountain
environment. Tourists can also capture repeat photography, and may also have
the opportunity to capture aerial imagery from helicopter flights, which can be
used to reconstruct the environment in 3D. There are opportunities for everyone
to engage with research that is ultimately geared towards improving our
understanding of global change and how best to adapt.
C. Scott Watson is an environmental research scientist and runs the outreach
website RockyGlaciers.co.uk. Tweets
@CScottWatson. This article follows the publication of ‘Everest's thinning
glaciers: implications for tourism and mountaineering’ in the journal Geology
Today http://onlinelibrary.wiley.com/doi/10.1111/gto.12215/full
